1. Field of the Invention
The present invention relates to an image presentation apparatus for presenting two-dimensional (2-D) images using a display whose position and orientation are variable.
2. Description of the Prior Art
There have been devised various interactive user interface techniques by building up a virtual space of three-dimensional (3-D) world and showing as if the user were present inside a virtual world.
With respect to the technique for changing the position of the viewpoint and eye direction in the virtual world, there has been contrived "head fitting type display". This is to detect the position and orientation of the user's head in the real world, to project the virtual world on the image according to the detection result, and to present the image on the display set before the eyes of the user. Alternatively, in order to realize the similar effect in more simple manner, there has been reviewed a procedure to detect the position and orientation of the user's head along with the orientation of the eyeballs, to form images according to the detection result, and to display said images on a conventional "desk-top type display".
On the other hand, as a technique for manipulating the object in the virtual world, "data gloves" are contrived, This is a system to have the user put on gloves provided with the position and orientation sensors on the corresponding positions of joints to monitor the movements of hands and fingers, and to utilize the movements and shapes as input information data. By this device, manipulation can be performed on the objects in the virtual world in the sense equivalent to that in the real world. Alternatively, devised is a procedure wherein the user is caused to manipulate input means specifically designed to the position and the orientation (for example, 3-D mouse), the position and orientation thereof are detected, and the detection results are used as the input information. Furthermore, use of the conventional input methods such as keyboard, mouse, and the like is also practiced.
However, the procedures as described above involve the following problems. The "head fitting type display" has problematic points in complication of fitting and unfitting and discomfort during fitting, and it is not suited for frequent use or long time sustaining use. Also, as it covers the user's field of view, danger caused by an obstacle in the real world cannot be neglected. Furthermore, in order to provide sufficient image quality to simulate the whole field of view, the display of very high resolution is required, which is restrained by the calculation cost for creating the resolution of the display device and image formation. The procedure to form images in conformity with the position and orientation of the head along with the eyeball orientation and display on a "desk-top type display" gives restriction to the range of vision, and cannot be an effective method.
The "data gloves" system also involves problems in complication of fitting and unfitting and discomfort during fitting. The said method requires calculation one by one of the transmission of forces at the contact points between the hand and the object with respect to the individual object, and it requires high calculation cost. In the case of using the input means specified to the position and the orientation, manipulation must be made in a place other than the place where the image is displayed, so it cannot be referred to as an intuitive manipulation. The procedures using the conventional input methods including a keyboard, mouse, etc. result in no realistic manipulation because of the necessity to convey to the computer the user's intention by abstract expression such as input of coordinate amounts.
To construct an interactive interface based on the 3-D space by using a simple device has diversified applications. For example, in the virtual reality field, it is an essential technique to have intuitive spatial cognition and carry out interactive object manipulation in a virtual 3-D world, and it is desired to realize such technique in a small scale system such as a mobile terminal. Further, if it becomes possible to extract accurately the information obtained from the complicated 3-D structure without necessitating to learn special skills, such technique can be applied to the field such as image analysis for medical use. In view of such a situation, it is a significant task to construct a spatial interface which can be easily used and is characteristic of natural and effective space formation and response to motion.